[Office upload] Use fake Drive classes in DriveUploadHandlerTest

Use FakeSimpleDriveFs and FakeSimpleDriveFsHelper in
DriveUploadHandlerTest to:
- SetMetadata() for a file being synced to fake Drive.
- GetMetadata() of a file on fake Drive.

This replaces the use to FakeDriveFs which differs in GetMetadata():
- FakeDriveFs: only returns FILE_ERROR_NOT_FOUND if the file is not in
  local storage. It doesn't matter if there is no metadata for the file
  on Drive.
- FakeSimpleDriveFs: returns FILE_ERROR_NOT_FOUND if there is no
  metadata for the file on Drive.

FakeSimpleDriveFs is a better choice for the tests that will be
introduced in b/244396230 to check whether a file has been synced to
fake Drive or not based on the GetMetadata result.

Bug: b/244396230
Change-Id: I0f7bdeb22df8a0189b41e700826d138fa002986b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4728581
Reviewed-by: Jeremie Boulic <jboulic@chromium.org>
Commit-Queue: Cassy Chun-Crogan <cassycc@google.com>
Cr-Commit-Position: refs/heads/main@{#1178226}